US3627944A - Sensing and control apparatus for webs - Google Patents

Abstract

A sensing and control apparatus for detecting thickness irregularities or the like in webs, such as paper webs. The apparatus includes a reference roller rotatably mounted about a fixed horizontal axis, and a motion detector roller mounted for vertical shifting movement, the rollers being adapted to lie tangent to a web disposed therebetween. A cross-shaft is provided, the shaft being mounted for rotation about a horizontal axis parallel with the axis of rotation of the rollers. Follower means on the cross-shaft engage on seats provided on the detector roller, such that upward movement of either end of the roller caused by a flaw in the web will induce a rotation of the shaft. The connection between the follower and roller is such as to permit pivotal movement about an axis essentially perpendicular to the pivot axis of the cross-shaft. Motion magnifying means for operating a cutoff switch are connected to the cross-shaft.

Description

United States Patent Hogget a1 200/61.13X

3,364,527 1/1968 Ramo 19/65CRX 3,502,827 3/1970 Beebe Primary ExaminerRobert K. Schaefer Assistant Examiner-M. Ginsburg Attorney-Arthur B. Colvin ABSTRACT: A sensing and control apparatus for detecting thickness irregularities or the like in webs, such as paper webs. The apparatus includes a reference roller rotatably mounted about a fixed horizontal axis, and a motion detector roller mounted for vertical shifting movement, the rollers being adapted to lie tangent to a web disposed therebetween. A cross-shaft is provided, the shaft being mounted for rotation about a horizontal axis parallel with the axis of rotation of the rollers. Follower means on the cross-shaft engage on seats provided on the detector roller, such that upward movement of either end of the roller caused by a flaw in the web will induce a rotation of the shaft. The connection between the follower and roller is such as to permit pivotal movement about an axis essentially perpendicular to the pivot axis of the cross-shaft. Motion magnifying means for operating a cutoff switch are connected to the cross-shaft.

PATENIEUUEBMIQYI D 3527944 sum l-UF 4 I. I nhi- INVI'IN'I'UR. DONALD G. FIELD ATTORNEY PATENTEnnEcmmn 3521944 sum 3 0F 4 INVHN'I'UIL DONALD G. FIELD SENSING AND CONTROL APPARATUS FOR WEBS This invention is in the field of apparatus for detecting thickness variations in webs or the like. Such thickness variations may be the result of detritus, slivers or like elements which are not integrated into the web or may be the result of the uneven formation of the web itself.

There is a growing market for prepackaged towels, dressings and like articles which comprise severed lengths of web material which have been folded or otherwise processed and sealed or encapsulated within foil or like envelopes. Such envelopes may or may not incorporate a liquid reagent which saturates the towel or dressing, in accordance with its intended end use.

It is highly desirable that the web material, which is to be subsequently folded and packaged, be controlled as to its thickness and be free from detritus, slivers or other extraneous matter. The importance of the requirement that the packaged process be free from detritus will be readily appreciated when it is realized that the finished products may be used as eye swabs, dressings, bandages, vaginal wipes and the like.

Since the web material used in the formation of such products is typically folded along a multiplicity or lengthwisely extending fold lines, it will be readily appreciated that a thickness area within the web itself which may happen to coincide with a fold line will, at best, result in.the production of an article having an exaggerated thickness, due to the fact that subsequent folding steps magnify the thickness of the web in areas in registry with the defective area. Since such products are typically fed through a fan folding apparatus for the formation of the longitudinal folds, if the high bulk defective area of the web should coincide with a fold area, it is conceivable that the material may jamwithin the fan folding apparatus, requiring a significant interruption in production to permit the jam to be cleared. I

Attempts have heretofore been made toprovide high-speed sensing apparatuses which may automatically interrupt production when detritus or an overthick portion of,a web is sensed. Such apparatuses have incorporated electric eye sensors, black spot sensors, as well as a variety of mechanical sensors. However, in practiceno mechanical detector heretofore known has been capable of .the simultaneous advantages of high accuracy, ready adjustment in accordance with the desired dimensional range, speed, and ability to sense a defect at any position along the entire width of the web. This last mentioned requirement has been particularly troublesome in 1 that, where mechanical detectors heretofore known have been able to sense a thickness variation at one widthwise position along a web, no such known apparatus has been equally sensitive across the entire width of the web.

The present invention relates to an automatic thickness detector responsive to a predetermined range of thickness variables, whether by way of integral defects in the web or detritus deposited on the web. The apparatus will sense a thickness variation without regard to its position transversely of the web.

The apparatus includes a pair of rollers or like means, one

I of which is preferably fixed for rotation about a reference axis.

selected magnitude, will trip the switch to effect a desired result, such as interruption of the web feed, etc.

It is accordingly an object of the invention to .provide a web thickness detector or the like which is simple in construction, and which may be readily modified to process webs of a variety of thicknesses.

A further object of the invention is to provide a detector of the type described which may be readily adjusted to control the permitted range of thicknesses and the extent of defects which will be tolerated.

A further object of the invention is the provision'of a device of the type described which will permit detection of a defe'ctat any position along the width of the continuously advancing web.

Still a further object of the invention is the provision of a device of the type described which is simple in construction durable, and preferably employs means to yieldingly urge the rollers toward each other.

To attain these objects and such further objects as may appear herein or be hereinafter pointed out, reference is made to the accompanying drawings, forming a part hereof, in'which:

FIG. I is a side elevational view of a web detector apparatus of the type described;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a magnified plan view of the section between the arrows 3-3 of FIG. 1;

FIG. 4 is a discontinuous vertical section taken on the staggered line 44 of FIG. 3,

FIG. 5 is a magnified vertical section taken on the line 5-5 of FIG. 3;

FIG. 6 is a magnified detail view of the control mechanism and the limit switch, and

FIG. 7 is a detail view taken along line 7-7 of FIG. I.

Referring now to the drawings, there is shown in FIG. I a web detector apparatus incorporated as an initial station in a mechanism for forming packets. In such packet forming apparatus, the web W is led from a supply roll S, through the detector assembly 10, and then to fan folding apparatus 11 which forms no part of the present invention.

The fan folder, as best seen in FIG. 2, takes the full width web and forms a multiplicity of longitudinally extending folds thereon, to form a multiple-ply folded web suitable for packaging in a small envelope.

The web supply roll S incorporates a support shaft 12 seated within spaced-apart, upwardly open bearing seats 13, permitting the supply roll to be mounted by lowering it into position. The web material may be payed off from the supply roll S by a pulling force, it being appreciated that by reason of the considerable weight of the supply roll, a fairly substantial tension is induced in the web in the course of such pulling.

It will be further appreciated that, despite considerable manufacturing care, the web in the bulk supply S may incorporate detritus by way of slivers, splinters or the like which may be either loosely appended to the surface of the web or adhered to or embodied in the web. As an initial means for reducing the amount of loosely carried detritus, the frame 14 of the detector apparatus is provided with a scraper assembly 15.

The scraper assembly includes an elongated substantially rectangular arm 16, the lower end 17 of which is mounted to a trunnion l8, suitably pivotally carried by spaced bearings formed on the frame. A spring 19 is tensioned between the spring seat 20 on vertical strut 2 1 of the frame and an adjustable seat 22 movably mounted on the arm 16, the spring 19 serving to impart an anticlockwise rotation to the arm 16 when the same is viewed as shown in FIG. 1.

At the upper end 23 of the arm 16, there is carried a scraper blade assembly 24 comprising a block 240 pivoted as at 24b and which carries a scraper blade 246, which is yieldingly urged against the periphery of the web W as it is unrolled from the bulk supply 8.

Furthermore, the upper end of arm 16 carries a pair of tapered rollers 16a which ride against the sides of the supply roll S to center the latter.

It will be appreciated that the scraper blade 24c will remove loosely entrained detritus from the surface of the web which is scanned by the blade, the spring 19 serving to maintain the scraper head in engagement with the web despite the progressively diminishing size of the bulk supply roll S.

In addition to scraper assembly 15, there is a second scraper assembly 15' which reacts against the opposite side of the web. This assembly may comprise a blade 15a secured by screws 15b in elongated adjustment slots 15c so that the edge or the blade may lightly contact the web surface.

The web W passes from the bulk supply roll S between a pair of rollers and 26, the lower roller 25 being referred to hereinafter as a reference roller, and the upper roller 26 being referred to as a detector roller. The rollers 25, 26 are rotatably mounted on the frame for rotation about horizontal, vertically spaced-apart axes.

Reference roller 25 comprises the roller over which the web W is pulled from the supply roll S, the detector roller 26 functioning as a detector in the manner hereinafter set forth.

Reference roller 25 is driven solely through the force exerted on the web and illustratively has no independent drive means.

Reference roller 25 is journaled in such manner as to have its uppermost surface or peripheral portion constantly disposed in a preselected horizontal reference plane. In contrast, the detector roller 26, as best seen in FIG. 5, is mounted in such manner as to permit vertical shifting movement thereof. To this end, detector frame 28 is provided with a pair of spaced, parallel side guides 29, 29, within which are formed vertically directed guideway channels 30. Guide blocks 31, 31 include slide portions 32 extending into the channels to permit the desired independent vertical movement of each end of the shaft while preventing rotary tilting of the blocks with respect to the channels.

The blocks 31 include bearing portions 33 which rotatably carry the distal ends 34, 34 of the detector roller 26.

A wiper blade member 35, illustratively a nylon strip, is provided, which performs the function of clearing any lint, detritus or the like from the surface of the detector roller 26. The blade 35 includes a clamped'end 36 which is bolted to the frame between upper and lower spacer blocks 37, 38, which blocks are held to the frame by clamp bolts 39.

The blade 35 includes a free end 40 which curls over, wipingly engages, and downwardly, yieldingly presses against the upper surface of detector roller 26. Preferably the width of the blade 35 is greater than the width of any web which will be fed in the apparatus so that it may perform its lint gathering functions across the entire widthwise extent of the web.

Means are provided for varying the cleaning force exerted by the free end 40 of wiper blade 35. For this purpose, a pair of stanchions 41, 41 are fixed to the frame adjacent the lateral portions 42, 43 of the blade 35. Each of the stanchions carries a collar 44, which collar portions may be heightwisely adjusted in relation to the stanchions 41. Each of the collars 44, 44 is connected to the opposite end of adjustment bar 45 which extends transversely beneath an undersurface portion of the blade 35.

It will be appreciated that the lower limit of movement of the blade 35 will be defined by the heightwisely adjusted position of the bar 45 which forms a lower stop portion for the blade. The bar 45 is adjusted by setting the position of the collars 44, in such manner that the free end 40 of the blade will press downwardly against the roller 26 with a desired force.

It is further important that the apparatus be responsive to a lifting of any portion of the upper roller, whereby the apparatus is sensitive to thickness variations appearing at any transverse position across the width of the web W.

The sensing apparatus includes a shaft 46 extending through and pivotally mounted within coaxially aligned bearings 47, 47 formed in the side frame portions 29. A pair of cap members 48, 48 is fixed to the distal ends of the shaft 46 which project beyond the sides 29, the caps carrying rearwardly directed extensions 49, 49 disposed in a substantially horizontal plane. The extensions 49 carry longitudinally adjustable weights 50, 50 which, when viewed in the orientation of FIG. 1, would ordinarily tend to impart an anticlockwise rotation to the shaft 46. Such anticlockwise rotation of the shaft is resisted by force transmission or follower members extending between the shaft 46 and seat or saddle supports 51, 51 formed at the upper ends of the slide blocks 31, 31.

As best shown in FIGS. 3 and 4, a follower 52, made fast to the shaft 46 and extending at right angles therefrom, is seated in the saddle 51 of the left-handmost block 31 having slide portion 32. A second follower 54 made fast to shaft 46 and extending at right angles therefrom is seated on the saddle 51 of the right-handmost block 31. The follower 54 has a rearwardly extension which defines a motion magnifying arm 53.

The follower 52 is keyed to the shaft 46 against relative movement, as by locking bolt 55. In similar fashion, locking bolt 56 keys the follower 54 and its associated motion magnifying arm 53 to the shaft 46.

The end 57 of the motion magnifying arm 53 is spaced a considerable distance from the axis of the shaft 46, the spacing between said shaft axis and the end 57 being considerably greater than the spacing between the shaft axis and the points of engagement of the follower portions 52 and 54 with their respective slide blocks.

From the foregoing it will be appreciated that a relatively small vertical movement imparted to either follower will induce a rotation of the shaft and cause a concomitantly far larger movement of the end 57 of the motion magnifying arm 53.

It will be apparent that, so long as the thickness of the web W passing between the rollers 25, 26 remains a constant, the axis of the detector roller 26 will remain in a predetermined vertical plane; the weights 50 normally urging the roller 26 against the surface of the web riding around roller 25. However, it will be understood further that in the event of a thickness variation in the web or the passage of detritus between the rollers, the axis of the detector roller 26 will be elevated or tilted within a vertical plane common to the axes of the rollers 25, 26. It is the function of the detecting and control mechanism next to be described to respond to any such lifting movements of the detector roller 26, and where such movements exceed a predetermined tolerance range, to change the sense of a switch set to effect a desired control function.

The control function in the illustrated embodiment is performed by a limit switch 58 carried on the indicator subassembly 59. The arm 53 carries a pair of collars 60, 60 which function longitudinally to locate therebetween a pivotal link 61 mounted in head 61'.

A switch operator rod 62 extends upwardly from the upper end of the link 61, the rod 62 being mounted for sliding movement within an opening 62' formed in a horizontal element 63 of the detector mechanism 59. A switch operator rod 64 extending through a bearing 64 is pivotally mounted in a head 64" carried by the upper end of rod 62.

It will be appreciated that by a vertical adjustment of rod 62 with respect to heads 61' and 64", precise control may be achieved in respect of the amount of vertical movement of the rod 62 which is required to activate (or deactivate) the switch 58. Preferably, an indicator light 65, alone or coupled with some audible alarm means, is provided to apprise the operator that thickness tolerances within the web have been exceeded. Obviously, the mechanism for communicating mechanical motion from the arm to the switch may be varied without departing from the spirit of the invention.

Normally, the switch 58 is operably connected to the circuit controlling the drive means (not shown) for web W in such manner that further feed of the web is interrupted immediately after a flaw or defect is sensed. As a result of this arrangement the flaw within the web will always be located slightly downstream of the mating area of the rollers 25, 26. Accordingly; the operator will be able to search the web in such area and, in the event that the defect is manually removable, attend thereto. In the event of serious defects, it may be necessary to cut out the offending portions of the web and rethread trailing web portions.

The apparatus preferably includes an indicator assembly 66 which provides continuous and highly accurate monitoring of the thickness of material extending between the rollers 25 26. The indicator apparatus includes a scale 67 having a pointer 68 which is pivoted at 69 at a pivot point which is adjacent one end 70 of the pointer.

The link element 71 is pivotally connected at its lower end 72 to the end 57 of the motion magnifying arm 53, the upper end 73 of the link being connected adjacent the end 70 of the pointer 68.

It will thus be appreciated that the indicator assembly 66 provides a further motion magnification such that even slight vertical movements of the motion magnifying arm 53 which may be insufficient to trip the switch 58 will nonetheless be sufficient to induce considerable movements of the end 74 of the pointer 68.

The web, after passing through the rollers 25, 26 preferably extends over a horizontally disposed idler roller 75, under a dancer roller 76, and over a second trailing idler 77. The dancer roller 76, in the usual manner, is permitted a range of vertical movement while maintaining a constant tension on the web.

A lower limit switch element 78 may be disposed in the path of the roller 76 at a lower limiting position thereof. Optionally, the switch 78 may be employed to interrupt the flow of motive power to the web drive (not shown) for a predetermined period of time since tripping of the switch 78 indicates an excess of the web material.

The web emerging from the roller 77 is passed to the fan fold assembly 11 and thence to the remainder of the packaging or other processing apparatus which, in the normal course, functions to sever discrete lengths of the web emerging from the fan folder, stuff and discrete lengths into suitable envelopes or the like, and thereafter seal the envelopes. Prior to sealing the envelopes, a reagent may be added to the envelopes.

The severing, filling, saturating and sealing steps are beyond the purview of the present application and are mentioned by way of illustration only.

From the foregoing it will be appreciated that there is provided in accordance with the present invention, a combined detector and indicator apparatus which is effective to sense thicknesses in excess of a reference thickness and visually to display such thickness variation on an indicator dial or interrupt a circuit, or both.

The thickness variation will be sensed without regard to its widthwise position on the web by reason of the unique interconnecting linkage between the sensing roller and the controlindicator apparatus.

Referring particularly to FIGS. 3 and 4, for instance, should a defect occur toward the left-hand side of the web, a clockwise tilting of the detector roller 26 will result in transmission of a rotary force to the shaft 46 through the follower 52.

Should the defect be nearer to the right hand side of the web, a similar rotation of the shaft 46 will result, the rotation in this instance being effected in response to the connection between the shaft 26 and block 31.

In the event of a centrally located defect, bodily upward movement (unaccompanied by substantial tilting) will also cause a rotation of the shaft 46, effected as a result of the combined action of both of the follower portions 52 and 54.

While the illustrated embodiment of the apparatus is provided with both switching and constant dimension monitoring functions, it will be obvious from the foregoing disclosure that an apparatus displaying only one of the noted functions is within the spirit of the present invention.

The apparatus is simple, foolproof, and readily adapted for processing of webs of a wide variety of thicknesses and widths.

Having thus described my invention, what I claim as new and desire to receive by Letters Patent of the United States is:

l. A sensing and control device for detecting thickness irregularities and the like at any position across the width of a web of substantial transverse dimension, comprising: a frame, a reference roller mounted to said frame for rotation about a fixed horizontal reference axis, a motion detector roller havin an axis spaced vertically above said reference roller, a pair 0 mounting means slldably guided in said frame for independent vertical shafting movement, said mounting means including generally horizontally disposed seat portions, bearing means on each of said mounting means for rotatably supporting the opposite ends of said detector roller, with the axes of said rollers in parallel relation, web feed means for advancing said web between said rollers with adjacent peripheral portions of said rollers tangentially engaging opposite faces of said web, a cross-shaft mounted on said frame for pivotal movement about a horizontal axis, a pair of parallel follower means extending from opposite ends of said shaft, said follower means being supported in respective seat portions of said mounting means, the connection between said follower means and seat portions causing pivotal movement of said follower means and said shaft when said mounting means shifts about a horizontal axis normal to the axis of said cross-shaft, pressure means yieldingly urging said follower means against said mounting means, motion magnifying means operably connected to said shaft for movement responsive to pivotal movements of said shaft, and a switch means actuated responsive to predetermined movements of said magnifying means.

2. The device in claim 1 and including a spring blade member yieldingly urged against said detector roller, said blade member engaging substantially the entire upper face of said roller, thereby to clear detritus therefrom.

3. The device in accordance with claim 1 and including indicator means operatively connected to said motion magnifying means, said indicator means including additional motion magnifier means. I

I i II t

Claims (3)

1. A sensing and control device for detecting thickness irregularities and the like at any position across the width of a web of substantial transverse dimension, comprising: a frame, a reference roller mounted to said frame for rotation about a fixed horizontal reference axis, a motion detector roller having an axis spaced vertically above said reference roller, a pair of mounting means slidably guided in said frame for independent vertical shifting movement, said mounting means including generally horizontally disposed seat portions, bearing means on each of said mounting means for rotatably supporting the opposite ends of said detector roller, with the axes of said rollers in parallel relation, web feed means for advancing said web between said rollers with adjacent peripheral portions of said rollers tangentially engaging opposite faces of said web, a cross-shaft mounted on said frame for pivotal movement about a horizontal axis, a pair of parallel follower means extending from opposite ends of said shaft, said follower means being supported in respective seat portions of said mounting means, the connection between said follower means and seat portions causing pivotal movement of said follower means and said shaft when said mounting means shifts about a horizontal axis normal to the axis of said cross-shaft, pressure means yieldingly urging said follower means against said mounting means, motion magnifying means operably connected to said shaft for movement responsive to pivotal movements of said shaft, and a switch means actuated responsive to predetermined movements of said magnifying means.

2. The device in claim 1 and including a spring blade member yieldingly urged against said detector roller, said blade member engaging substantially the entire upper face of said roller, thereby to clear detritus therefrom.

3. The device in accordance with claim 1 and including indicator means operatively connected to said motion magnifying means, said indicator means including additional motion magnifier means.

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